picturebox上画图用api怎么实现

[Sunny21]

程序如下，执行一点反应都没有
Private Structure POINTAPI
Public x As Integer
Public y As Integer
End Structure

Private Sub DrawPictureBox2()
Dim i As Integer
Dim j As Byte
Dim tempPOINTAPI As POINTAPI
Dim tempPen As Integer
tempPen = CreatePen(0, 1, RGB(255, 0, 0))
SelectObject(PictureBox1.Handle.ToInt32, tempPen)
MoveToEx(PictureBox1.Handle.ToInt32, 10, 10, tempPOINTAPI)
LineTo(PictureBox1.Handle.ToInt32, 50, 50)
End Sub

[pupo]

直接用gdi+咯

[pupo]

Dim myPen As Pen

Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
myPen = New Pen(Color.Red)
myPen.Width = 5
End Sub

Private Sub Form1_Closing(ByVal sender As Object, ByVal e As System.ComponentModel.CancelEventArgs) Handles MyBase.Closing
myPen.Dispose()
End Sub

Private Sub PictureBox1_Paint(ByVal sender As Object, ByVal e As System.Windows.Forms.PaintEventArgs) Handles PictureBox1.Paint
e.Graphics.DrawLine(myPen, 1, 1, 200, 200)
e.Graphics.DrawArc(myPen, 100, 100, 100, 50, 60, 180)
End Sub

[pupo]

你在Paint事件里面画看看

[Sunny21]

直接用gdi+当然简单了，但我要画的波形最大有256K，通过水平和垂直滚动条连续画后续的波形，内存占用不断升级，程序反应迟钝
Private Sub DrawPictureBox2()
Dim tempPOINTAPI As POINTAPI
Dim tempPen As Integer
Dim tempHDC As Integer
tempHDC = GetDC(PictureBox1.Handle.ToInt32)

tempPen = CreatePen(0, 1, RGB(255, 0, 0))
SelectObject(tempHDC, tempPen)
MoveToEx(tempHDC, 10, 10, tempPOINTAPI)
LineTo(tempHDC, 50, 50)
ReleaseDC(PictureBox1.Handle.ToInt32, tempHDC)
End Sub
上面的代码已经可以实现，但是一旦窗体失去焦点，画的图形就会消失，是不是需要用临时文件存储，再赋给picturebox1.image??????

[malingxian]

绘制图形应该在控件的OnPaint时间里面进行比较好。
或者你可以用API建立一个虚拟位图，绘制到虚拟位图里面，然后用graphics.image=虚拟位图即可，速度快且不闪烁。

[weixinzhu]

onpaint事件或者是用bitmap

[初冬雪]

好帖子,我保留下来 !